1. Field of the Invention
The present invention relates to a method and an apparatus for cutting a raw material belt-like member to obtain desired product belt-like members and also forming inclined surfaces for jointing at the cut end portions of the product belt-like members, for instance, upon manufacture of tires.
2. Description of the Prior Art
W the manufacture of tires, a raw material belt-like member made of unvulcanized rubber is cut to obtain belt-like members having a predetermined length, and steps of wrapping this belt-like member around a drum having a circumferential length equal to the length of the belt-like member with its opposite ends jointed together and press-jointing the both end portions, are carried out.
Generally, in the case of jointing the opposite end portions of a belt-like member 01 or end portions of two belt-like members 01, 01, lap joint in which end portions are in themselves overlapped as shown in FIG. 8A, is frequently used, but in this lap joint a thickness of a jointed portion becomes twice as thick as that of the other portion, hence an inner structure is varied due to volume change of that portion, and it would adversely affect the product Especially in the case of manufacturing a tire, the above-mentioned volume change would adversely affect uniformity and balance of the tire.
In addition, butt joint as shown in FIG. 8B is also employed, but this butt joint is technically accompanied by difficulties as a jointing method at the time of forming a thin belt-like member of unvulcanized rubber into a cylindrical shape, and especially in the case of a tire, since the belt-like member is subjected to various external forces and deformation before completion, the butt joint is not suitable in view of a mechanical strength.
In FIG. 8C is shown taper joint, wherein taper-shaped inclined surfaces 02 are formed at the end portions to be jointed with each other and the opposite end portions are jointed together via these inclined surfaces. With this taper joint, a volume change would not occur as is the case with the above-described lap joint. Also a jointing surface area becomes broad as compared to the above-described butt joint, and a jointing force is increased by the corresponding amount. However, in the prior art, since the inclined surface 02 was formed by cutting the belt-like member 01 obliquely with respect to the direction of thickness by means of a cutter, an inclination angle could not be made a small angle of, for instance, 20.degree. or less. There is thus a limit in the increase of a jointing surface area and a jointing force. In addition, since the inclination angle .alpha. is large, even if the end portions should deviate a little, poor jointing portions such as steps or vacancies (opened) or the like would be liable to occur, hence in order to remedy such poor jointing portions so that the jointing portions may not adversely affect the performance after the belt-like members had been matured into a product tire, surplus man-hours were necessitated in the next step of the process.